Air-fuel ratio correction method, device, apparatus, and storage medium

Abstract

The present application belongs to the technical field of vehicle control, and discloses a kind of air-fuel ratio correction method, device, equipment and storage medium.The present application is connected nitrogen oxygen sensor after the catalytic converter of vehicle, and obtains the engine speed and air flow of the current time of vehicle engine;According to the engine speed and the air flow, the corresponding nitrogen oxygen correction value is found in the correction parameter table corresponding to the nitrogen oxygen sensor;According to the nitrogen oxygen correction value, the air-fuel ratio of vehicle is corrected.Since nitrogen oxygen sensor is set after air-fuel ratio sensor and catalytic converter to replace post oxygen sensor to correct air-fuel ratio, full-time correction is realized, which is more conducive to the control of pollutants during emission.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vehicle control, in particular to an air-fuel ratio correction method, device, equipment and storage medium. BACKGROUND

[0002] The engine exhaust system of a vehicle usually uses the value collected by an upstream air-fuel ratio sensor as the air-fuel ratio to feedback control the operation of the engine. However, due to manufacturing errors and other reasons, there is actually a certain deviation between the air-fuel ratio signal fed back by the air-fuel ratio sensor and the value of the true air-fuel ratio. Directly controlling the operation of the engine according to the air-fuel ratio signal fed back by the air-fuel ratio sensor will lead to poor emission effect. Therefore, the value of the air-fuel ratio sensor needs to be corrected.

[0003] At present, the air-fuel ratio collected by the air-fuel ratio sensor is usually corrected by a rear oxygen sensor arranged downstream of the air-fuel ratio sensor. However, the rear oxygen sensor has certain problems, which lead to unsatisfactory correction effect: the rear oxygen sensor is of the switching type and can only feed back rich and lean signals. The transient value is not reliable, accurate quantitative feedback cannot be achieved, and the learning speed is slow. The rear oxygen sensor has a long closed-loop time, and the optimization effect on emissions during the cold start stage is not obvious. The catalytic converter (TWC) has an oxygen storage function, which will cause a delay in correction based on the rear oxygen sensor and make real-time correction impossible. If the TWC deteriorates, the collected value of the rear oxygen sensor will fluctuate sharply, which cannot play a correction role.

[0004] The above content is only used to assist in understanding the technical solutions of the present application and does not mean that the above content is prior art. SUMMARY

[0005] The main purpose of the present application is to provide an air-fuel ratio correction method, device, equipment and storage medium, which aims to solve the technical problem of unsatisfactory air-fuel ratio correction effect based on the rear oxygen sensor in the prior art.

[0006] To achieve the above-mentioned purpose, the present application provides an air-fuel ratio correction method, which is applied to a vehicle, and a nitrogen oxygen sensor is connected to the rear end of the catalytic converter of the vehicle.

[0007] The air-fuel ratio correction method comprises the following steps:

[0008] Obtaining the engine speed and air flow of the vehicle engine at the current time;

[0009] Looking up the corresponding nitrogen oxygen correction value in the correction parameter table corresponding to the nitrogen oxygen sensor according to the engine speed and the air flow;

[0010] Correcting the air-fuel ratio of the vehicle according to the nitrogen oxygen correction value.

[0011] Optionally, the step of correcting the air-fuel ratio of the vehicle according to the nitrogen oxide correction value further comprises:

[0012] obtaining a current speed and a current intake amount of the engine of the vehicle;

[0013] finding a corresponding optimal nitrogen oxide emission amount in a preset emission calibration table according to the current speed and the current intake amount;

[0014] obtaining a current nitrogen oxide emission amount according to a current collection value of the nitrogen oxide sensor;

[0015] determining a correction learning coefficient according to the current nitrogen oxide emission amount and the optimal nitrogen oxide emission amount;

[0016] updating a correction parameter table corresponding to the nitrogen oxide sensor according to the current speed, the current intake amount and the correction learning coefficient.

[0017] Optionally, the step of finding a corresponding optimal nitrogen oxide emission amount in a preset emission calibration table according to the current speed and the current intake amount further comprises:

[0018] obtaining a corresponding oxygen storage capacity stage of the catalytic converter;

[0019] finding a corresponding preset emission calibration table according to the oxygen storage capacity stage.

[0020] Optionally, the step of obtaining a current speed and a current intake amount of the engine of the vehicle comprises:

[0021] detecting a running state of the nitrogen oxide sensor and an engine state of the vehicle;

[0022] obtaining a current speed and a current intake amount of the engine of the vehicle when detecting that a running temperature of the nitrogen oxide sensor reaches a dew point temperature and that the engine of the vehicle is warmed up.

[0023] Optionally, the step of determining a correction learning coefficient according to the current nitrogen oxide emission amount and the optimal nitrogen oxide emission amount further comprises:

[0024] calculating a difference between the current nitrogen oxide emission amount and the optimal nitrogen oxide emission amount;

[0025] if the difference is greater than a preset correction threshold, performing the step of determining a correction learning coefficient according to the current nitrogen oxide emission amount and the optimal nitrogen oxide emission amount.

[0026] Optionally, the step of determining a correction learning coefficient according to the current nitrogen oxide emission amount and the optimal nitrogen oxide emission amount comprises:

[0027] calculating a difference ratio between the current nitrogen oxide emission and the optimal nitrogen oxide emission;

[0028] comparing the difference ratio with a preset ratio threshold value;

[0029] if the difference ratio is greater than the preset ratio threshold value, setting a correction learning coefficient as a first learning coefficient;

[0030] if the difference ratio is less than or equal to the preset ratio threshold value, setting the correction learning coefficient as a second learning coefficient, the first learning coefficient being greater than the second learning coefficient.

[0031] Optionally, the step of correcting the air-fuel ratio of the vehicle according to the nitrogen oxide correction value comprises:

[0032] acquiring an oxygen concentration value collected by the nitrogen oxide sensor when it is detected that the nitrogen oxide sensor is heated up;

[0033] determining an oxygen correction value according to the oxygen concentration value;

[0034] correcting the air-fuel ratio of the vehicle according to the oxygen correction value and the nitrogen oxide correction value.

[0035] In addition, to achieve the above object, the present application further provides an air-fuel ratio correction device, which comprises the following modules:

[0036] a data acquisition module, configured to acquire an engine speed and an air flow of a vehicle engine at a current time;

[0037] a data searching module, configured to search for a corresponding nitrogen oxide correction value in a correction parameter table corresponding to the nitrogen oxide sensor according to the engine speed and the air flow;

[0038] a data correction module, configured to correct the air-fuel ratio of the vehicle according to the nitrogen oxide correction value.

[0039] In addition, to achieve the above object, the present application further provides an air-fuel ratio correction device, which comprises a processor, a memory and an air-fuel ratio correction program stored in the memory and executable on the processor, and the air-fuel ratio correction program realizes the steps of the air-fuel ratio correction method when executed by the processor.

[0040] In addition, to achieve the above object, the present application further provides a computer readable storage medium, which stores an air-fuel ratio correction program, and the air-fuel ratio correction program realizes the steps of the air-fuel ratio correction method when executed.

[0041] This invention connects a nitrogen oxide sensor to the rear end of the vehicle's catalytic converter and acquires the engine speed and airflow at the current moment. Based on the engine speed and airflow, it looks up the corresponding nitrogen oxide correction value in the correction parameter table corresponding to the nitrogen oxide sensor. The air-fuel ratio of the vehicle is then corrected according to the nitrogen oxide correction value. Because the nitrogen oxide sensor is placed after the air-fuel ratio sensor and catalytic converter to replace the oxygen sensor for air-fuel ratio correction, it achieves full-time-domain correction, which is more beneficial for controlling pollutants during emissions. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the structure of an electronic device in the hardware operating environment involved in the embodiments of the present invention;

[0043] Figure 2 This is a flowchart illustrating the first embodiment of the air-fuel ratio correction method of the present invention;

[0044] Figure 3 This is a schematic diagram showing the location of the nitrogen and oxygen sensor according to an embodiment of the present invention;

[0045] Figure 4 This is a flowchart illustrating the second embodiment of the air-fuel ratio correction method of the present invention;

[0046] Figure 5 This is a schematic diagram of the air-fuel ratio correction execution process according to an embodiment of the present invention;

[0047] Figure 6 This is a schematic diagram of the nitrogen and oxygen correction value learning process according to an embodiment of the present invention;

[0048] Figure 7 This is a structural block diagram of the first embodiment of the air-fuel ratio correction device of the present invention.

[0049] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0050] It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0051] Reference Figure 1 , Figure 1 This is a schematic diagram of the air-fuel ratio correction device structure in the hardware operating environment involved in the embodiments of the present invention.

[0052] like Figure 1As shown, the electronic device may include: a processor 1001, such as a central processing unit (CPU), a communication bus 1002, a user interface 1003, a network interface 1004, and a memory 1005. The communication bus 1002 is used to enable communication between these components. The user interface 1003 may include a display screen or an input unit such as a keyboard; optionally, the user interface 1003 may also include a standard wired interface or a wireless interface. The network interface 1004 may optionally include a standard wired interface or a wireless interface (such as a Wireless-Fidelity (Wi-Fi) interface). The memory 1005 may be high-speed random access memory (RAM) or stable non-volatile memory (NVM), such as a disk drive. The memory 1005 may also optionally be a storage device independent of the aforementioned processor 1001.

[0053] Those skilled in the art will understand that Figure 1 The structure shown does not constitute a limitation on the electronic device and may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0054] like Figure 1 As shown, the memory 1005, which serves as a storage medium, may include an operating system, a network communication module, a user interface module, and an air-fuel ratio correction program.

[0055] exist Figure 1 In the electronic device shown, the network interface 1004 is mainly used for data communication with the network server; the user interface 1003 is mainly used for data interaction with the user; the processor 1001 and the memory 1005 in the electronic device of the present invention can be set in the air-fuel ratio correction device. The electronic device calls the air-fuel ratio correction program stored in the memory 1005 through the processor 1001 and executes the air-fuel ratio correction method provided in the embodiment of the present invention.

[0056] This invention provides an air-fuel ratio correction method, referring to... Figure 2 , Figure 2 This is a schematic flowchart of the first embodiment of the air-fuel ratio correction method of the present invention.

[0057] The air-fuel ratio correction method is applied to vehicles, where a nitrogen oxide sensor (NOx sensor) is connected to the rear end of the catalytic converter. Compared with the existing solution, the rear oxygen sensor, which was originally located after the air-fuel ratio sensor (A / F sennor, AFS) and the catalytic converter (TWC), is replaced with a nitrogen oxide sensor.

[0058] To facilitate understanding, we will now combine... Figure 3 This explanation is provided, but it does not limit the scope of this solution. Figure 3 This is a schematic diagram showing the location of the nitrogen and oxygen sensor in this embodiment, as shown below. Figure 3 As shown, the vehicle's exhaust system is connected to an air-fuel ratio sensor. Figure 3 The air-fuel ratio sensor is followed by a catalyst (TWC), and a nitrogen oxide sensor (NOXSensor) is followed by the nitrogen oxide sensor. A catalyst TWC can also be placed after the nitrogen oxide sensor.

[0059] In this embodiment, the air-fuel ratio correction method includes the following steps:

[0060] Step S10: Obtain the current engine speed and airflow of the vehicle engine.

[0061] It should be noted that the execution subject of this embodiment can be the air-fuel ratio correction device or the vehicle itself. The air-fuel ratio correction device can be a controller in the vehicle, such as an ECU controller or other functions. This embodiment does not limit this. In this embodiment and the following embodiments, the air-fuel ratio correction device is used as an example to illustrate the air-fuel ratio correction method of this application.

[0062] It should be noted that the current engine speed of the vehicle engine can be obtained by reading the current value collected by the vehicle's speed sensor. The current airflow of the vehicle engine can be obtained by measuring the amount of air intake per unit time, for example, the amount of air intake into the vehicle engine in 1 second. Of course, airflow can also be the current air intake rate of the vehicle engine; this embodiment does not limit this.

[0063] Step S20: Based on the engine speed and the air flow rate, find the corresponding nitrogen and oxygen correction value in the correction parameter table corresponding to the nitrogen and oxygen sensor.

[0064] It should be noted that the nitrogen oxide correction value can be the correction value when adjusting the air-fuel ratio based on the data collected by the nitrogen oxide sensor. The correction parameter table can be a data table used to store the nitrogen oxide correction values ​​corresponding to the nitrogen oxide sensor. The correction parameter table can be pre-calibrated by the administrator of the air-fuel ratio correction equipment. The horizontal axis of the data table can be engine speed, and the vertical axis can be air flow. The specific values ​​of the table entries are nitrogen oxide correction values. Of course, the horizontal and vertical axes can be interchanged, and this embodiment does not limit this.

[0065] In practical use, the correction parameter table can be stored in the air-fuel ratio correction device in the form of a map set (with the engine speed value and air flow value as the key in the map set, and the nitrogen oxide correction value as the value corresponding to the key in the map set).

[0066] Step S30: Correct the vehicle's air-fuel ratio according to the nitrogen-oxygen correction value.

[0067] It should be noted that correcting the vehicle's air-fuel ratio based on the nitrogen oxide correction value can be done by adding the nitrogen oxide correction value to the vehicle's air-fuel ratio, and using the sum as the corrected vehicle air-fuel ratio.

[0068] In practical use, the air-fuel ratio of a vehicle can be the value collected by the vehicle's air-fuel ratio sensor. Of course, if the value collected by the air-fuel ratio sensor cannot be obtained (such as when the air-fuel ratio sensor is not installed in the vehicle or the air-fuel ratio sensor is damaged), the theoretical air-fuel ratio can also be calculated based on the vehicle's parameters and the type of fuel used, and the calculated theoretical air-fuel ratio can be used as the vehicle's air-fuel ratio.

[0069] If gasoline is used, the theoretical air-fuel ratio can be set to 14.7; if diesel is used, the theoretical air-fuel ratio can be set to 14.2; and if other types of fuel are used, the theoretical air-fuel ratio can be calculated using the air-fuel ratio calculation formula.

[0070] The formula for calculating the air-fuel ratio is:

[0071] AFS t =34.41×(g) C / 3+g H -g O / 8)

[0072] In the formula, AFS t Theoretical air-fuel ratio; g C The mass percentage of carbon in the fuel; g H The mass percentage of hydrogen in the fuel; g O This represents the mass percentage of oxygen in the fuel.

[0073] In practice, after obtaining the corrected air-fuel ratio of the vehicle, the engine parameters, such as the fuel injection quantity and intake air quantity, can be adjusted to make the actual air-fuel ratio of the vehicle closer to the theoretical air-fuel ratio.

[0074] In this embodiment, a nitrogen oxide sensor is connected to the rear end of the vehicle's catalytic converter. The system acquires the engine speed and airflow at the current moment. Based on the engine speed and airflow, the system looks up the corresponding nitrogen oxide correction value in the correction parameter table corresponding to the nitrogen oxide sensor. The air-fuel ratio of the vehicle is then corrected according to this correction value. Because the nitrogen oxide sensor is installed after the air-fuel ratio sensor and catalytic converter to replace the oxygen sensor for air-fuel ratio correction, full-time-domain correction is achieved, which is more beneficial for controlling pollutants during emissions.

[0075] refer to Figure 4 , Figure 4 This is a flowchart illustrating a second embodiment of an air-fuel ratio correction method according to the present invention.

[0076] Based on the first embodiment described above, the air-fuel ratio correction method of this embodiment further includes, after step S30:

[0077] Step S40: Obtain the current engine speed and current air intake of the vehicle.

[0078] It should be noted that the current engine speed of the vehicle can be the engine speed at the current moment, and the current intake air volume of the vehicle can be the air flow of the vehicle at the current moment. The method of obtaining these values ​​is similar to that described above, and will not be repeated here.

[0079] Furthermore, to ensure the effectiveness of learning the nitrogen and oxygen correction values, step S40 in this embodiment may include:

[0080] The operating status of the nitrogen oxide sensor and the engine status of the vehicle are detected;

[0081] When the operating temperature of the nitrogen-oxygen sensor is detected to have reached the dew point temperature, and the engine of the vehicle has completed warm-up, the current speed and current intake air volume of the vehicle engine are obtained.

[0082] It should be noted that to ensure the stability of the nitrogen oxide correction value learning, it is necessary to learn based on relevant data during stable operation. The nitrogen oxide sensor will only operate stably and collect data after its operating temperature reaches the dew point temperature. Similarly, it can only be guaranteed to operate stably after the engine has warmed up. Therefore, the nitrogen oxide correction value learning steps can be performed only when the operating temperature of the nitrogen oxide sensor reaches the dew point temperature and the vehicle's engine has warmed up, so as to ensure the effectiveness of the nitrogen oxide correction value learning as much as possible.

[0083] Similarly, since engine stability is affected by changes in engine speed or intake air volume exceeding a certain threshold, after obtaining the current engine speed and intake air volume, these values ​​can be compared with previous values ​​to determine the magnitude of the speed and intake air volume changes. Furthermore, it can be detected whether the speed and intake air volume changes are less than preset threshold values. Only when both the speed and intake air volume changes are below these threshold values, indicating engine stability, will subsequent steps proceed. Both the preset speed and intake air volume change thresholds can be pre-set by the air-fuel ratio correction device administrator.

[0084] Step S50: Based on the current rotational speed and current intake air volume, find the corresponding optimal nitrogen oxide emission in the preset emission calibration table.

[0085] It should be noted that the preset emission calibration table can be a data table storing the optimal nitrogen oxide emissions under various operating conditions (different engine speeds, different airflow rates). The nitrogen oxide emissions can include the content of various nitrogen oxide compounds in the exhaust, such as NO2 and NO3. The preset emission calibration table can be pre-calibrated by the personnel managing the air-fuel ratio correction equipment. The horizontal axis of the preset emission calibration table can be engine speed, and the vertical axis can be airflow rate. The values ​​in each table entry are the optimal nitrogen oxide emissions. Of course, the horizontal and vertical axes can be interchanged, and this embodiment does not impose any restrictions on this.

[0086] In practical implementation, finding the optimal nitrogen oxide emission rate in the preset emission calibration table based on the current engine speed and current intake air volume can be achieved by searching for entries in the preset emission calibration table where the engine speed matches the current speed and the corresponding airflow matches the current intake air volume. The value stored in these entries is then used as the corresponding optimal nitrogen oxide emission rate. Specifically, the preset emission calibration table can also be stored as a map set in the air-fuel ratio correction device. The specific set construction method is similar to that of the correction parameter table mentioned above, and will not be elaborated further here.

[0087] Furthermore, to ensure the accuracy of the correction learning as much as possible, the following steps may be included before step S50 in this embodiment:

[0088] The stage for obtaining the oxygen storage capacity corresponding to the catalyst;

[0089] Find the corresponding preset emission calibration table based on the oxygen storage capacity stage.

[0090] It should be noted that since nitrogen oxide (NOx) emissions vary depending on the level of use of the catalyst, the oxygen storage capacity of the catalyst can be divided into several different stages (e.g., fresh, intermediate, and aged) based on its level of use, and different preset emission calibration tables can be set for each stage. This ensures that the optimal NOx emissions obtained during the actual learning process match the level of use of the catalyst.

[0091] In practical use, the oxygen storage capacity stage of a catalytic converter can be determined by obtaining the total driving distance of the vehicle after the catalytic converter is installed. For example, if the lifespan of the catalytic converter is X, then after installation, if the total driving distance is less than X / 3, the oxygen storage capacity stage is considered fresh; if the total driving distance is greater than or equal to X / 3 but less than 2X / 3, the oxygen storage capacity stage is considered mid-term; and if the total driving distance is greater than or equal to 2X / 3, the oxygen storage capacity stage is considered aging. Alternatively, the oxygen storage capacity stage can be determined by obtaining the total usage time of the catalytic converter (or other data that represents the catalytic converter's lifespan).

[0092] Step S60: Obtain the current collected value of the nitrogen and oxygen sensor to obtain the current nitrogen and oxygen emissions.

[0093] It should be noted that obtaining the current nitrogen and oxygen emission amount by acquiring the current value collected by the nitrogen and oxygen sensor can be achieved by reading the nitrogen and oxygen concentration value currently collected by the nitrogen and oxygen sensor and using the collected nitrogen and oxygen concentration value as the current nitrogen and oxygen emission amount.

[0094] Step S70: Determine the correction learning coefficient based on the current nitrogen and oxygen emissions and the optimal nitrogen and oxygen emissions.

[0095] It should be noted that determining the correction learning factor based on the current nitrogen oxide emissions and the optimal nitrogen oxide emissions can be done by calculating the difference between the current nitrogen oxide emissions and the optimal nitrogen oxide emissions, and then finding the corresponding correction learning factor based on this difference.

[0096] In a specific implementation, step S70 of this embodiment may include:

[0097] Calculate the percentage difference between the current nitrogen oxide emissions and the optimal nitrogen oxide emissions;

[0098] Compare the difference ratio with a preset ratio threshold;

[0099] If the difference ratio is greater than the preset ratio threshold, the corrected learning coefficient is set as the first learning coefficient.

[0100] If the difference ratio is less than or equal to the preset ratio threshold, the corrected learning coefficient is set as the second learning coefficient.

[0101] It should be noted that the ratio of the difference between the current nitrogen oxide emissions and the optimal nitrogen oxide emissions can be calculated as the absolute value of the difference between the current nitrogen oxide emissions and the optimal nitrogen oxide emissions. The ratio of this absolute value to the optimal nitrogen oxide emissions is then used as the ratio. The preset ratio threshold, the first learning coefficient, and the second learning coefficient can all be preset by the administrator of the air-fuel ratio correction device. The first learning coefficient is greater than the second learning coefficient, and the preset ratio threshold can be set to 20%.

[0102] It should be understood that if the difference ratio is greater than the preset ratio threshold, it means that the difference between the two is large and rapid learning is required. Therefore, a larger step size can be used for learning so that the corrected value approaches the actual value more quickly. In this case, the correction learning coefficient can be set to a larger first learning coefficient. Conversely, if the difference ratio is less than or equal to the preset ratio threshold, it means that the difference between the two is small. In this case, a smaller compensation can be used for learning. Therefore, the correction learning coefficient can be set to a smaller second learning coefficient.

[0103] Furthermore, to reduce unnecessary calculations, the following steps may be included before step S70 in this embodiment:

[0104] Calculate the difference between the current nitrogen oxide emissions and the optimal nitrogen oxide emissions;

[0105] If the difference is greater than a preset correction threshold, then the step of determining the correction learning coefficient based on the current nitrogen and oxygen emissions and the optimal nitrogen and oxygen emissions is executed.

[0106] It should be noted that the preset correction threshold can be set in advance by the administrator of the air-fuel ratio correction equipment. When determining the correction learning coefficient based on the current nitrogen oxide emissions and the optimal nitrogen oxide emissions, various calculations and data lookups are required, which consumes equipment resources and takes a certain amount of processing time. If the difference between the current nitrogen oxide emissions and the optimal nitrogen oxide emissions is less than a certain amount, the correction value will not be updated. To reduce unnecessary calculations and save time and equipment resources, before formally determining the correction learning coefficient, the difference between the current nitrogen oxide emissions and the optimal nitrogen oxide emissions can be calculated first. If the difference is less than or equal to the preset correction threshold, it indicates that the difference between the two is already small, and subsequent steps can be omitted.

[0107] If the difference is greater than the preset correction threshold, it means that the difference between the two is large and learning is required. In this case, the step of determining the correction learning coefficient based on the current nitrogen and oxygen emissions and the optimal nitrogen and oxygen emissions can be performed.

[0108] Since the difference has already been calculated, the absolute value can be directly calculated using this difference. Then, the absolute value can be divided by the optimal nitrogen and oxygen emission to determine the difference ratio, thereby minimizing unnecessary calculations.

[0109] Of course, if the preset correction threshold is set directly based on the difference, it will be difficult to set the threshold when both values ​​are small. In this case, the preset correction threshold can be set as a percentage. Before determining whether to look up the correction learning coefficient, the difference ratio between the current nitrogen oxide emission and the optimal nitrogen oxide emission is calculated. Only when the difference ratio is greater than the preset correction threshold is the step of determining the correction learning coefficient based on the current nitrogen oxide emission and the optimal nitrogen oxide emission executed.

[0110] Step S80: Update the correction parameter table corresponding to the nitrogen and oxygen sensor according to the current rotation speed, the current intake volume and the correction learning coefficient.

[0111] It should be noted that updating the correction parameter table corresponding to the nitrogen oxide sensor based on the current speed, current intake volume, and correction learning coefficient can be done by obtaining the entries corresponding to the current speed and current intake volume in the correction parameter table of the nitrogen oxide sensor, multiplying the nitrogen oxide correction value in the entry by the correction learning coefficient to obtain the learning value, and updating the nitrogen oxide correction value in the entry to the sum of the nitrogen oxide correction value and the learning value in the entry.

[0112] Of course, in practice, the corrected learning coefficient can also be set to the value that actually needs to be updated. In this case, the nitrogen and oxygen correction value in the table can be directly updated to the sum of the corrected learning coefficients of the nitrogen and oxygen correction value in the table.

[0113] In a specific implementation, to prevent the exhaust system from becoming too rich, after step S30 in this embodiment, the following may also be included:

[0114] When the nitrogen and oxygen sensor is detected to have finished heating, the oxygen concentration value collected by the nitrogen and oxygen sensor is obtained;

[0115] Determine the oxygen correction value based on the oxygen concentration value;

[0116] The vehicle's air-fuel ratio is corrected based on the oxygen correction value and the nitrogen-oxygen correction value.

[0117] It should be noted that the nitrogen and oxygen sensor can be considered to have finished heating when it is detected that the nitrogen and oxygen sensor has heated up to the preset operating temperature.

[0118] In actual use, even after correcting the vehicle's air-fuel ratio based on the nitrogen oxide correction value, the exhaust system may still be too rich. To avoid this, a corresponding correction value can be set based on the oxygen concentration value. During the actual correction, the corresponding correction value (oxygen correction value) can be found by combining the collected oxygen concentration value. The vehicle's air-fuel ratio can then be corrected based on both the oxygen and nitrogen oxide correction values ​​to prevent the exhaust system from becoming too rich.

[0119] The nitrogen-oxygen sensor can only collect oxygen concentration values ​​after heating is complete. Therefore, the oxygen concentration value collected by the nitrogen-oxygen sensor can be obtained after heating is complete, and the corresponding oxygen correction value can be found based on the oxygen concentration value.

[0120] Of course, since the nitrogen and oxygen sensor cannot guarantee normal collection of oxygen concentration values ​​before it has finished heating up, directly preset correction values ​​may lead to correction anomalies. Therefore, it is also possible not to preset correction values ​​corresponding to oxygen concentration values ​​(i.e., not to store correction values ​​corresponding to oxygen concentration values ​​locally or in memory), but to set up a fast learning mode, starting from 0 each time, and updating the oxygen correction values ​​corresponding to oxygen concentration values ​​through automatic learning. The learning method is similar to the learning method of nitrogen and oxygen correction values, and will not be described in detail here.

[0121] To facilitate understanding, we will now combine... Figure 5 and 6 This explanation does not limit the scope of this solution. Figure 5 This is a schematic diagram of the air-fuel ratio correction execution process in this embodiment. Figure 6 This is a schematic diagram of the nitrogen and oxygen correction value learning process in this embodiment.

[0122] like Figure 5 As shown, after the vehicle's engine starts, the engine operating condition (engine speed ENGRPM and air flow) can be identified first. Then, based on the engine operating condition, the corresponding NOx correction value is found in the map set storing NOx correction values ​​(FACNOX). The vehicle's air-fuel ratio (AFRSEN) is then corrected based on this NOx correction value. At this point, the actual air-fuel ratio FARACT = AFRSEN + FACNOX. After the NOx sensor has finished heating and starts working, the oxygen concentration value (O2MV) is collected. A short-term learning value update is performed based on the O2MV output to obtain the oxygen correction value (FACO2). The vehicle's air-fuel ratio is then corrected based on the oxygen correction value and the NOx correction value to obtain the actual air-fuel ratio.

[0123] like Figure 6As shown, after the vehicle's engine starts, once the NOx sensor dew point temperature is reached (if not reached, the NOx sensor continues to heat), the NOx sensor is initialized and begins measuring the concentration of nitrogen oxides (NOx) to obtain NOx PPM. Then, after the engine warm-up is complete (if not complete, the engine continues to warm up), the engine operating conditions (engine speed ENGRPM and engine intake air flow rate AIRFLOW) are identified. The engine speed change DENGRPM is calculated based on ENGRPM, and the engine intake air volume change DAIRFLOW is calculated based on the engine intake air flow rate. If DENGRPM < a preset value (i.e., a preset speed change threshold) and DAIRFLOW < a preset value (i.e., a preset intake air volume change threshold), then learning the AFR correction coefficient based on NOx concentration begins (the fFACNOX value is modified to 1, as shown in the table). (This indicates that the NOx correction coefficient learning state is established.) Then, based on the catalyst's oxygen storage capacity stages (including fresh, mid-term, and aging stages), the optimal NOx emission map (i.e., the preset emission calibration table) is found. Next, the optimal NOx emission NOXTRGT (i.e., optimal nitrogen oxide emission) is found. Then, the difference between the actual NOx value and the optimal NOx emission target value (i.e., the difference ratio) is calculated. If the NOx difference is greater than the internal reserved value (i.e., the preset correction threshold), the absolute value of the NOx difference is checked to see if it is greater than 20%. If yes, the correction coefficient is set to FACNOXQ; otherwise, it is set to FACNOXS. Then, the actual learned value FACNOXFL is output based on the correction coefficient. Based on the learned value, the values ​​corresponding to ENGRPM and AIRFLOW in the correction parameter table map are updated to FACNOXFL + FACNOX. In the figure, FACNQX_M is the updated correction parameter table map.

[0124] This embodiment obtains the current engine speed and current air intake of the vehicle; searches for the corresponding optimal nitrogen oxide emission level in a preset emission calibration table based on the current engine speed and current air intake; obtains the current collected value of the nitrogen oxide sensor to obtain the current nitrogen oxide emission level; determines the correction learning coefficient based on the current nitrogen oxide emission level and the optimal nitrogen oxide emission level; and updates the correction parameter table corresponding to the nitrogen oxide sensor based on the current engine speed, the current air intake, and the correction learning coefficient. Since the optimal nitrogen oxide emission level is also found based on the current engine speed and current air intake, and compared with the actual collected current nitrogen oxide emission level, and the correction parameter table corresponding to the nitrogen oxide sensor is updated based on the comparison result, the actual nitrogen oxide emissions are used as an indicator for reverse updating and control, effectively reducing pollutant emissions, especially nitrogen oxide emissions.

[0125] Furthermore, embodiments of the present invention also propose a storage medium storing an air-fuel ratio correction program, wherein when the air-fuel ratio correction program is executed by a processor, it implements the steps of the air-fuel ratio correction method described above.

[0126] Reference Figure 7 , Figure 7 This is a structural block diagram of the first embodiment of the air-fuel ratio correction device of the present invention.

[0127] like Figure 7 As shown, the air-fuel ratio correction device proposed in this embodiment of the invention includes:

[0128] Data acquisition module 10 is used to acquire the engine speed and air flow of the vehicle engine at the current moment;

[0129] The data lookup module 20 is used to look up the corresponding nitrogen oxide correction value in the correction parameter table corresponding to the nitrogen oxide sensor based on the engine speed and the air flow rate;

[0130] The data correction module 30 is used to correct the vehicle's air-fuel ratio based on the nitrogen-oxygen correction value.

[0131] In this embodiment, a nitrogen oxide sensor is connected to the rear end of the vehicle's catalytic converter. The system acquires the engine speed and airflow at the current moment. Based on the engine speed and airflow, the system looks up the corresponding nitrogen oxide correction value in the correction parameter table corresponding to the nitrogen oxide sensor. The air-fuel ratio of the vehicle is then corrected according to this correction value. Because the nitrogen oxide sensor is installed after the air-fuel ratio sensor and catalytic converter to replace the oxygen sensor for air-fuel ratio correction, full-time-domain correction is achieved, which is more beneficial for controlling pollutants during emissions.

[0132] Furthermore, the data correction module 30 is also used to obtain the current engine speed and current air intake of the vehicle engine; look up the corresponding optimal nitrogen oxide emission in a preset emission calibration table based on the current engine speed and current air intake; obtain the current collected value of the nitrogen oxide sensor to obtain the current nitrogen oxide emission; determine the correction learning coefficient based on the current nitrogen oxide emission and the optimal nitrogen oxide emission; and update the correction parameter table corresponding to the nitrogen oxide sensor based on the current engine speed, the current air intake, and the correction learning coefficient.

[0133] Furthermore, the data correction module 30 is also used to obtain the oxygen storage capacity stage corresponding to the catalyst; and to look up the corresponding preset emission calibration table according to the oxygen storage capacity stage.

[0134] Furthermore, the data correction module 30 is also used to detect the operating status of the nitrogen-oxygen sensor and the engine status of the vehicle; when it is detected that the operating temperature of the nitrogen-oxygen sensor has reached the dew point temperature and the engine of the vehicle has completed warm-up, it acquires the current speed and current intake air volume of the vehicle engine.

[0135] Furthermore, the data correction module 30 is also used to calculate the difference between the current nitrogen oxide emissions and the optimal nitrogen oxide emissions; if the difference is greater than a preset correction threshold, then the step of determining the correction learning coefficient based on the current nitrogen oxide emissions and the optimal nitrogen oxide emissions is executed.

[0136] Furthermore, the data correction module 30 is also used to calculate the difference ratio between the current nitrogen oxide emission and the optimal nitrogen oxide emission; compare the difference ratio with a preset ratio threshold; if the difference ratio is greater than the preset ratio threshold, then set the correction learning coefficient as a first learning coefficient; if the difference ratio is less than or equal to the preset ratio threshold, then set the correction learning coefficient as a second learning coefficient, wherein the first learning coefficient is greater than the second learning coefficient.

[0137] Furthermore, the data correction module 30 is also used to acquire the oxygen concentration value collected by the nitrogen-oxygen sensor when the nitrogen-oxygen sensor is detected to have finished heating; determine an oxygen correction value based on the oxygen concentration value; and correct the vehicle air-fuel ratio based on the oxygen correction value and the nitrogen-oxygen correction value.

[0138] It should be understood that the above are merely illustrative examples and do not constitute any limitation on the technical solution of the present invention. In specific applications, those skilled in the art can make settings as needed, and the present invention does not impose any restrictions on this.

[0139] It should be noted that the workflow described above is merely illustrative and does not limit the scope of protection of this invention. In practical applications, those skilled in the art can select some or all of the workflow to achieve the purpose of this embodiment according to actual needs, and no restrictions are imposed here.

[0140] In addition, for technical details not described in detail in this embodiment, please refer to the air-fuel ratio correction method provided in any embodiment of the present invention, which will not be repeated here.

[0141] Furthermore, it should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0142] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0143] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as read-only memory (ROM) / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal device (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0144] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A method for correcting air-fuel ratio, characterized in that, The air-fuel ratio correction method is applied to a vehicle, wherein a nitrogen oxide sensor is connected to the rear end of the catalytic converter. The air-fuel ratio correction method includes the following steps: Obtain the current engine speed and airflow of the vehicle's engine; Based on the engine speed and the air flow rate, the corresponding nitrogen oxide correction value is found in the correction parameter table corresponding to the nitrogen oxide sensor; The vehicle's air-fuel ratio is corrected based on the stated nitrogen oxide correction value; The step of correcting the vehicle's air-fuel ratio based on the nitrogen oxide correction value further includes: The operating status of the nitrogen oxide sensor and the engine status of the vehicle are detected; When the operating temperature of the nitrogen oxide sensor is detected to have reached the dew point temperature, and the engine of the vehicle has finished warming up, the current speed and current intake air volume of the vehicle engine are obtained. The optimal nitrogen oxide emission is found in the preset emission calibration table based on the current speed and current air intake. The preset emission calibration table is a data table that stores the optimal nitrogen oxide emission under each operating condition. Obtain the current collected value of the nitrogen and oxygen sensor to obtain the current nitrogen and oxygen emissions; The correction learning coefficient is determined based on the current nitrogen and oxygen emissions and the optimal nitrogen and oxygen emissions. Obtain the entries corresponding to the current speed and current intake volume in the correction parameter table of the nitrogen and oxygen sensor, and multiply the nitrogen and oxygen correction value in the entries with the correction learning coefficient to obtain the learning value; The nitrogen and oxygen correction value in the table entry is updated to the sum of the nitrogen and oxygen correction value in the table entry and the learning value.

2. The air-fuel ratio correction method as described in claim 1, characterized in that, Before the step of finding the corresponding optimal nitrogen oxide emission amount in the preset emission calibration table based on the current rotational speed and current intake air volume, the method further includes: The stage for obtaining the oxygen storage capacity corresponding to the catalyst; Find the corresponding preset emission calibration table based on the oxygen storage capacity stage.

3. The air-fuel ratio correction method as described in claim 1, characterized in that, Before the step of determining the corrected learning coefficient based on the current nitrogen and oxygen emissions and the optimal nitrogen and oxygen emissions, the method further includes: Calculate the difference between the current nitrogen oxide emissions and the optimal nitrogen oxide emissions; If the difference is greater than a preset correction threshold, then the step of determining the correction learning coefficient based on the current nitrogen and oxygen emissions and the optimal nitrogen and oxygen emissions is executed.

4. The air-fuel ratio correction method as described in claim 1, characterized in that, The step of determining the correction learning coefficient based on the current nitrogen oxide emissions and the optimal nitrogen oxide emissions includes: Calculate the percentage difference between the current nitrogen oxide emissions and the optimal nitrogen oxide emissions; Compare the difference ratio with a preset ratio threshold; If the difference ratio is greater than the preset ratio threshold, the corrected learning coefficient is set as the first learning coefficient. If the difference ratio is less than or equal to the preset ratio threshold, the corrected learning coefficient is set as the second learning coefficient, and the first learning coefficient is greater than the second learning coefficient.

5. The air-fuel ratio correction method according to any one of claims 1-4, characterized in that, The step of correcting the vehicle's air-fuel ratio based on the nitrogen oxide correction value includes: When the nitrogen and oxygen sensor is detected to have finished heating, the oxygen concentration value collected by the nitrogen and oxygen sensor is obtained; Determine the oxygen correction value based on the oxygen concentration value; The vehicle's air-fuel ratio is corrected based on the oxygen correction value and the nitrogen-oxygen correction value.

6. An air-fuel ratio correction device, characterized in that, The air-fuel ratio correction device includes the following modules: The data acquisition module is used to obtain the current engine speed and airflow of the vehicle engine. The data lookup module is used to look up the corresponding nitrogen oxide correction value in the correction parameter table corresponding to the nitrogen oxide sensor based on the engine speed and the air flow. The data correction module is used to correct the vehicle's air-fuel ratio based on the nitrogen oxide correction value; The data correction module is also used to detect the operating status of the nitrogen oxide sensor and the engine status of the vehicle; when the operating temperature of the nitrogen oxide sensor reaches the dew point temperature and the engine of the vehicle has finished warming up, it acquires the current speed and current air intake of the vehicle engine; it searches for the corresponding optimal nitrogen oxide emission amount in a preset emission calibration table based on the current speed and current air intake amount; it acquires the current collected value of the nitrogen oxide sensor to obtain the current nitrogen oxide emission amount; The correction learning coefficient is determined based on the current nitrogen and oxygen emissions and the optimal nitrogen and oxygen emissions. Obtain the entries corresponding to the current speed and current intake volume in the correction parameter table for the nitrogen and oxygen sensor. Multiply the nitrogen and oxygen correction value in the entries by the correction learning coefficient to obtain the learning value. Update the nitrogen and oxygen correction value in the entries to the sum of the nitrogen and oxygen correction value in the entries and the learning value.

7. An air-fuel ratio correction device, characterized in that, The air-fuel ratio correction device includes: a processor, a memory, and an air-fuel ratio correction program stored in the memory and executable on the processor. When the air-fuel ratio correction program is executed by the processor, it implements the steps of the air-fuel ratio correction method as described in any one of claims 1-5.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores an air-fuel ratio correction program, which, when executed, implements the steps of the air-fuel ratio correction method as described in any one of claims 1-5.

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